Konzertmeister di Sinfonia Concertante
by Hitokun
Summary: Shuuichi is no competition at all for Kumiko's affections. Reina knows that all too well, but why does a spontaneous confession from Kumiko's childhood friend put doubt in Reina's mind? Reina x Kumiko


**Konzertmeister di Sinfonia Concertante**

* * *

"…So that's why I need to ask you for your help, Kousaka-san."

Reina looked over from the window, unamused. She raised an eyebrow as she met the boy's gaze. Did he not know how much she disliked him? Did he not know how many daggers she had glared his way every time he tried talking to Kumiko? It was tolerance.

An absence of hostility was not friendship.

Simply put, Kousaka Reina tolerated Tsukamoto Shuuichi because she had to. She knew that Kumiko valued him for some reason. Even though the euphonium player barely gave him the time of day, Reina could sense that Kumiko felt comfortable around him, a similar level of comfort that she had with Reina.

The dark haired beauty narrowed her eyes in disdain, just thinking about the possibility of someone like him being on the same level as her. It was unnerving to say the least. She wanted to be special.

She wanted to be special to Kumiko.

"So will you help me?"

Reina stared in silence, arching an eyebrow. She hadn't heard a word the boy had said to her over the last few minutes. The classroom was empty save for the two of them. It was so quiet that Shuuichi's uneven breathing was clearly audible.

"With?"

Shuuichi blinked once, then twice, staring blankly at the dark haired girl, wondering if she was just being difficult.

Seeing a stupid expression register on the boy's face, Reina sighed, feeling just a little bit sorry for him. "I wasn't paying attention earlier. Why did you approach me today?" She was frank, not wanting to waste time on niceties.

Not today.

And not with him.

"W-Well…uhh." The trombonist stuttered, feeling a bit self-conscious, regretting his decision to ask the ice queen for advice in the first place. It was just that every time he saw Kumiko with Reina, the trumpeter was always laughing and smiling, giving off a different air than she did now.

"Go on." Reina stared down the blond with an intimidating gaze.

"Err…I was just saying that…I need your help, Kousaka-san. I really like Kumiko and…"

Reina's eye twitched at that, her hostility growing as he continued to blabber on.

"I wanted to ask her to-"

"No." Reina said as she stood abruptly, struggling to keep her anger under control. It would be unsightly if she let this man get under her skin.

"B-But, Kousaka-san…you've been around Kumiko a lot lately and I just want-"

"I said no." Reina shouldered her bag, preparing to leave, checking her watch absently. It was nearly 6 o'clock. and Kumiko said she would be done by now.

"Wait, Kousaka! You didn't even hear what I wanted-" The blond reached out a hand to catch the girl who was making her way quickly to the door.

As soon as he touched her shoulder, Reina bristled, whipping around and slapping Shuuichi's hand away with more force than she intended.

"Please. Don't." Her words cut through the air.

The dark haired girl was too proud. She knew that what she was doing was ugly, but she just couldn't help herself. Something inside her erupted at the sight of the trombonist, at his words, at…his feelings towards Kumiko. This last point especially touched on a nerve.

 _Kumiko was hers, after all._

Shuuichi was taken aback, stepping away as he searched Reina's face for an answer. He was confused, wondering why this line of questioning elicited such a reaction.

There was a silence in the room, Reina's glowering violet eyes overshadowing Shuuichi's pale gold ones. Their gazes met in a clash, with the trumpeter gaining the upper hand.

"Reina! I just finished. I'm so sorry I made you wait. I –" Kumiko's voice rang out as the door slid open. The strangely bubbly brunette paused in her tracks as she came face to face with Reina and Shuuichi just a few feet from the door. "Uhm…Am I interrupting something here?" Her eyes darted to Reina first, then to Shuuichi. The two in front of her were standing strangely close, a thick tension in the air.

At the brunette's entrance, the two parties turned to face her, re-composing themselves.

"Kumiko! I-"

"Not at all. I'm glad to see you, Kumiko." Shuuichi was interrupted before he could get a word in edgewise. Reina broke contact with the boy, her expression doing a 360 as she turned to Kumiko. The heavy atmosphere dissipated. The black haired girl smiled at the brunette, ignoring the trombonist's presence.

"Me too, Reina." Kumiko smiled back warmly, captivated by the intensity in the other girl's eyes. There was a slight pause in the exchange before the two moved towards the door.

"Let's go, Reina. I'm starved!" Kumiko eagerly dragged the other girl along. "See you tomorrow, Shuuichi." Kumiko threw the boy a backhanded wave as she left with the Reina, not bothering to look back.

Still rooted to the spot, Shuuichi stared after them, still trying to register what happened. It was over in a flash, and it seemed like he was back to square one, but with Kousaka Reina as an enemy.

He didn't know what he did to get on her bad side.

Girls were…just so hard to understand.

* * *

"So…what did Shuuichi want, Reina?" Kumiko bit her lip as she skipped along, the question gnawing at the back of her mind. It wasn't that she wanted to pry, but…it was unusual and it made her feel uncomfortable. After all, Reina was her friend, wasn't she? She didn't know why Shuuichi would ever be interested in Reina. Sure, the girl was smart, talented, and drop dead gorgeous, but…

Kumiko suddenly paused.

That was the problem. There were no buts. Reina was nearly perfect.

Kumiko paled.

"Nothing. He just wanted to talk." Reina continued on unfazed, casually slipping her hand into Kumiko's as they made their way to the train station. They were the only ones in the school courtyard. School had finished hours ago, and only a few clubs were left on campus.

"Oh...I see. That's pretty out of the blue though…haha." Kumiko laughed nervously, feeling an awkward silence fall between them.

Stopping abruptly, Reina looked over at the euphonium player. "Is there something wrong, Kumiko?" The trumpet player's face was full of concern, her hand gripping Kumiko's tightly. Again, it was unnerving that Shuuichi created this mood between them.

The brunette took a deep breath, her heart racing in her chest for some odd reason. Reina's eyes seemed to pierce her soul, looking right past her indifference.

"It just…makes me uncomfortable, Reina. When I see you with him, my…my heart kinda…aches. I'm not sure why." Kumiko chuckled sheepishly, pulling her hands away from the other girl gently. The euphonium player walked ahead, feeling conflicted, embarrassed. "It sounds stupid…I know, but-"

"Kumiko! Wait up!"

Reina sighed heavily, shaking her head at the terrible luck she had today.

"Shuuichi?" Kumiko sounded more annoyed than anything as she watched the trombonist approach them in a half-jog.

"Kumiko, I'm so glad I caught you. Are you free tomorrow after school? There's something I need to talk to you about." A faint tinge of redness was on the boy's cheeks and Reina knew it wasn't from the short run he had just had.

"Uhm. Tomorrow…" Kumiko looked up, earnestly thinking about her schedule for the next few days. Before the brunette had a chance to really reply, Reina stepped in between the two.

"Sorry, but Kumiko has plans with me."

"I-I do?" The girl in question was taken off guard, pleasantly so, but it was an apprehensive type of elation. She loved it when Reina was like this. Kumiko felt her heart swell at the girl's words.

"Kousaka, I think you should let Kumiko speak for herself." Shuuichi was getting irritated, understanding that Reina was not just being difficult, but intentionally making things difficult for him.

" _Tsukamoto_." Reina enunciated every syllable, venom dripping from her words. "You need to get a hint. Kumiko is not interested in you. She will _never_ be interested in you."

Shuuichi flinched at the end of Reina's sentence, catching a glimpse of a sneer that the girl flashed him.

Kumiko was blushing now, feeling honored to be pulled out of her mundane routine. She was enjoying the show so far, more amused than anything.

Shuuichi was angry. He had always made sure he was the perfect gentleman in every situation, but in front of Kousaka Reina, _this_ version of Reina, he couldn't. If anything, he wanted to shove her aside so she would stop interfering in his attempts to talk to Kumiko.

"You don't know anything. I've been Kumiko's friend ever since she started playing the euphonium. Do you know how long that is? Do you even know anything about her? How would you know that she's not interested?" The blond was livid, pointing an accusatory finger at the black haired girl.

Kumiko looked on in shock, at what Shuuichi was implying. Reina was right though. She never had shown any interest in Shuuichi…

"Don't be stupid. You'd have to be blind not to see it. You're not worthy of her." Reina laughed condescendingly, shaking her head.

' _Reina'_ , Kumiko thought to herself, her heart racing. The other girl's conviction was riveting. If she had a say in this disagreement, the brunette was sure that she would side with Reina. After all, Reina was defending her. The euphonium player smiled, comparing Reina to a knight defending her lady's honor.

It was silly, but a lopsided grin was plastered on the brunette's face.

Shuuichi let out an exasperated groan, clenching his fists. He couldn't hit a girl, but he was so close to doing so. "Why are you acting like this, Kousaka? Do you have something against me? Who are you to say who would be worthy of Kumiko anyway?" The boy spoke like the girl in question wasn't even there.

Reina paused. She could feel Kumiko's eyes boring into her back. She could tell that the other girl was interested in what she had to say, the nervous apprehension floating in the air. With the brief silence, a sudden realization struck Reina.

Their flirtatious teasing had its limits, the sexual tension could have been misconstrued.

It was her chance, her chance to make Kumiko understand what her declaration of love really meant, that it was far from a joke. For a long time, the over-achieving trumpeter had been complacent with just being Kumiko's friend. It was a safe choice. It was a choice that allowed the both of them to support each other without any of that messy drama. Reina knew she was attracted to Kumiko and Reina knew Kumiko was attracted to her.

However, Reina wasn't quite sure that Kumiko herself was aware of their secret romance.

"Cat got your tongue, hm?" Shuuichi scoffed, feeling like he had finally gotten the upper hand.

Reina took a deep breath. She could kill two birds with one stone here, but she couldn't risk it. If on an off chance she was wrong about Kumiko's feelings, it would be the end.

"No." Reina stepped forward quite boldly, and the blond boy instinctively stepped back in response. With a smug smile on her face, Reina replied, "I know what Kumiko likes."

A barely audible gasp escaped the brunette's lips. _'That's hot…'_ Thought Kumiko as she chewed on her lip to stifle her gasp.

Shuuichi raised an eyebrow, almost challenging Reina to continue. "And what _does_ Kumiko like?"

" _Kumiko_." The dark haired girl paused.

Behind Reina, Kumiko shuddered involuntarily, electrifying pleasure running down her spine at the sound of her own name coming from the trumpeter's mouth. She felt like a deviant. Reina's voice was so alluring, making her feel desperate to understand why she felt so attracted to the girl in front of her.

"Kumiko likes ambition and confidence, not boring guys with no talent like you." Reina's words were harsh, but it was nothing short of the truth.

The trombonist shook his head, feeling the girl's words sting. He couldn't deny it. "I've been there for her. I'm her best friend. I'm a good guy." Shuuichi took a step forward, but Reina never wavered, standing her ground. The blond's gaze softened for a moment, almost desperate as he pleaded with Reina.

He then looked over to Kumiko, locking eyes with her. "Kumiko, I'm in love with you. I've been in love with you for as long as I've known."

The girl in question flushed a bright red, from her cheeks to the tips of her ears.

Reina was appalled. He was bold. Maybe even bolder than her.

Dumbstruck by the spontaneous confession, Reina offered no resistance when Shuuichi pushed past her to get to Kumiko. The trumpeter stumbled before righting her balance, her mind still a jumble as she witnessed what was going on.

Shuuichi was in front of Kumiko now, his hands grasping desperately for hers.

The sight made Reina's heart ache. Something about the look in Kumiko's eyes threw her off. It looked like the brunette was enjoying herself.

"Kumiko, will you go out with me?"

Reina didn't have a chance to see the expression on Kumiko's face at this moment, the expression that would have told Reina that there was no way she would ever consider Shuuichi's proposal.

Without another word, the black haired girl stormed through, yanking Kumiko away from the lovestruck boy.

It was a flurry of confusion, like a scene out of a movie as Reina held Kumiko possessively away from Shuuichi. Reina held the girl's waist with one hand and tipped her chin up with the other. The two were only centimeters apart, meeting each other's eyes. With one look, the trumpeter knew that she was wrong to doubt Kumiko for even a second.

She was right.

 _Kumiko was hers._

There was no need to continue, but Kousaka Reina loved to show off. She loved to show off and she couldn't resist smiling as she pressed her lips to Kumiko's. The kiss was everything Reina imagined and more. She couldn't believe that she had waited so long for this moment. It had to be the masochistic side of her that allowed her to abstain for so long before taking Kumiko for herself. It was a treat, an indulgent action.

Even with the boy still standing two feet away from them, staring in incredulity, his attention went unnoticed.

Reina continued to kiss Kumiko and Kumiko continued to kiss her back.

The black haired girl grinned, running her tongue across Kumiko's lips, insisting that she give her access. The brunette let slip a moan as she felt Reina's tongue push into her mouth.

It seemed like forever before the two parted, a wide grin on both their faces, laughter threatening to spill out. Neither of them had imagined that they would ever be kissing each other on the steps of the school courtyard. It was a new experience to say the least.

They both still had their eyes fixated on each other, not wanting to break away.

"A-ahem…"

The girls turned to the source of the voice, almost forgetting that they had an audience, slightly miffed that they couldn't continue making out in a public area.

Shuuichi knew he was fighting a losing battle, but he still had to try, otherwise he wouldn't be much of a man. "I just…want to know your final answer, Kumiko." The trombonist looked down, his cheeks red from embarrassment.

Reina rolled her eyes, but Kumiko simply smiled as she took a few steps towards him.

"Shuuichi."

The boy looked up, full of delusional hopefulness.

Before giving him an answer, Kumiko glanced back at the trumpeter, reaching over to lace Reina's fingers with her own.

A beaming smile on her face, Oumae Kumiko looked into Tsukamoto Shuuichi's eyes, and she had never been as sure as she was now.

"Sorry, Shuuichi." The brunette raised her right hand, tightly intertwined with Reina's, gesturing to it with a tilt of her head. "I'm taken, as you can see."

Admitting defeat, Shuuichi mustered up a weak smile before turning and leaving the two on their own.

Once the blond was out of earshot, the entire courtyard was empty. Kumiko and Reina shared a knowing smile before bursting into a fit of laughter.

Giddy with excitement, Kumiko leaned over to Reina, her lips grazing the girl's ear. " _I know what Reina likes_." The euphonium player mimicked Reina's earlier statement, sending shivers down the trumpeter's spine.

Reina smirked, her voice laced with anything but innocence. "Who knew you were such a bad girl, Kumiko."

"Just. For you." The brunette pressed her lips against Reina's neck, grinning into the kiss. " _I do know what you like after all."_

" _Pervert_." Reina returned the gesture, her words brushing past the nape of Kumiko's neck as she leaned in, whispering the word through her mischievous smile.

"And you're a self-proclaimed masochist, aren't you?" Kumiko teased as she thought back to the Agata festival, wondering if that was when she fell in love with Kousaka Reina.

It was love, wasn't it? If Kumiko had any doubts before, they were dispelled when Reina kissed her earlier.

"We're made for each other, like a symphony and a concerto." The smile was apparent in Reina's voice.

She pulled Kumiko along, wanting to scream into the heavens how ecstatic she was to finally have euphonium player to herself.

"A symphony and a concerto are two different things, Reina." Kumiko shook her head in amusement, wondering how the other girl could possibly think about music analogies at a time like this.

"Exactly. We're different, Kumiko, but when we come together, the music…is beautiful." The dark haired girl had a serious expression on her face and Kumiko stifled her laughter as she rolled her eyes slightly.

The whole ordeal was amusing to Kumiko, realizing that Kousaka Reina usually had everything under control, except when it came down to things that involved her.

Kumiko knew the truth.

Without warning, the brunette leaned over, taking Reina's lips with her own.

Oumae Kumiko discovered that she had the real control and she was certainly going to abuse her power.

* * *

 **A/N:** Tried to be fancy with the title lol. I have bad taste in titles. I mixed German and Italian together...It was totally intentional... :D

Sinfonia Concertante is a concerto that uses two or more solo instruments. The symphony and the concerto are two different types of pieces, with the concerto having the soloist in the spotlight and the symphony having a focus on the ensemble. I thought this was a cool representation of Kumiko and Reina, with Reina often stealing the spotlight as a soloist.

The ending was cheesy too haha...Forgive me :P

Oh yeah, standard disclaimers apply to all my stories. I've been forgetting to put that, but it should be obvious since this is a fanfiction website, right?

Anyway, I'm on some weird...binge writing campaign I guess. I'm not sure when this will end, but I'm going to ride the momentum while it lasts.

Review if you enjoyed this! Thanks :)


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